Time indicating labels are known. For example, U.S. Pat. No. 4,212,153 issued to Kydonieus, et al entitled teaches a time color indicator having a reservoir layer adhesively attached to an indicator layer. In accordance with the Kydonieus patent, a migrating agent in the reservoir layer migrates through the adhesive layer and the indicator layer to the top or front surface of the indicator layer. The Kydonieus patent also teaches that the reservoir layer is preferably mounted on a barrier layer with an adhesive and release sheet on top of the reservoir layer. The indicator is activated by removing the release sheet and applying an indicator layer to the adhesive layer.
Kydonieus further teaches that the indicator layer is a solid sheet or film of non-porous polymer which allows migration of the chosen agent, and that appropriate indicator layer materials include plasticized PVC, semi-plasticized PVC, rigid PVC, acrylics, polyurethanes and thermoplastic polyester elastomers. The Kydonieus indicator layer is 2 to 14 mils thick. The reservoir layer is preferably made from a plastisol, although vinyl chloride/vinyl acetate copolymer, a urethane polymer, a polyolefin, a thermoplastic polyester elastomer, and polyvinyl chloride may be used in forming the reservoir layer. Kydonieus teaches that the reservoir layer should be 1 to 20 mils thick, and is preferably 1 to 5 mils thick. One suggested application for the Kydonieus device is greeting cards
Variations on the Kydonieus device are taught in U.S. Pat. Nos. 5,974,003 and 7,215,604. However, none of these labels are adapted for attachment to tubing, e.g., tubing associated with intravenous (IV) bags, and similar structures. Disclosures that do teach methods for attaching a label to a wire or tube include U.S. Pat. Nos. 4,539,767, 5,092,066 and 7,073,282 but these methods of attachment do not allow for easy re-positioning of the label after attachment to the wire or tube.
Of continuing interest is a time indicating, or expiration indication, label that attaches easily to a tube, is easily re-positioned on the tube after attachment, can carry a graphic which can be applied before and/or after attachment to the tube, and provides a reliable and easily discernible indication of a pre-determined elapse of time.